V článku diskutujeme závislost výskytu nejzastoupenějších typů prostorových grup organických a organometalických látek na redukovaných objemech základních buněk, tj. pro typy prostorových grup Pï, P21, P21/c, C2/c, P212121 a Pbca do 8000 Å3. Pro každou prostorovou grupu jsou tyto závislosti podobné. Z těchto závislostí plyne, že organické a organometalické molekuly ztrácejí schopnost krystalizovat, pokud se objem redukované základní buňky blíží 8000 Å3. Tento objem odpovídá zhruba 450 nevodíkových atomům v základní buňce. z naší analýzy pak vychází úvaha o velikosti biologických molekul jako zábrany krystalizace v organismu., The dependences of occurrences of the most frequent space-group types Pï, P21, P21/c, C2/c, P212121 and Pbca on reduced unit-cell volumes up to 8000 Å3 have been investigated. From these dependences it can be inferred that the ability for crystallization of organic and metallorganic molecules ceases for structures with reduced unit-cell volumes above 8000 Å3. This volume corresponds roughly to 450 non-hydrogen atoms in a molecule. It follows from the analysis that the huge size of biological molecules may be due to hindrance of spontaneous crystallization of the molecules in the living organisms., Jan Fábry, Radmila Krupková., and Obsahuje bibliografii
Professor Pavel Zemanek and his colleagues at the Institute of Scientific Instruments (1St) of the ASCR built a laser that moves tiny spheres of polystyrene floating in water While in science fiction programs such as "Star Trek," tractor beams are used to move massive objects, the unique research published in Nature Photonics (2013, 7, 123-127) is limited to moving microscopic particles. Changing the way the light is polarized changes the direction the spheres move. The ISI scientists also found that at certain sizes, the spheres arrange themselves into neat rows as they move, bound by the light itself. The practical applications could be diverse. The tractor beam is very selective in the properties of the particles it acts upon, so one could pick up specific particles in a mixture. For example, this laser could be used to separate white blood cells. and Luděk Svoboda.